Evaluation of the Respiratory Effects of Driving Pressure Guided Mechanical Ventilation Using Electrical Impedance Tomography in Patients Undergoing Robot-Assisted Laparoscopic Radical Prostatectomy

General anesthesia increases the risk of respiratory complications and impairs arterial oxygenation by causing atelectasis in the dorsal regions of the lungs. Postoperative pulmonary complications (PPC) represent events such as atelectasis, pulmonary edema, pneumonia, pleuritis, reintubation, and the need for oxygen support after surgery, and are associated with increased morbidity, mortality, intensive care, and hospital stay durations, as well as higher healthcare costs. The effective strategy to reduce the incidence of PPC in patients under general anesthesia is still not clear.

Robot-assisted surgeries are increasingly preferred for prostatectomy, a curative treatment for prostate cancer, due to advantages such as less blood loss, less scar tissue formation, and shorter hospital stays compared to other surgical methods. During robotic surgery, many factors such as laparoscopy, pneumoperitoneum, and extreme Trendelenburg position can negatively affect lung function. Studies have shown that high driving pressure values, resulting from the set tidal volume target and PEEP values during mechanical ventilation, increase postoperative pulmonary complications.

Developing mechanical ventilation strategies based on personalized PEEP values that provide the lowest driving pressure after recruitment maneuvers to include closed alveoli in respiration and monitoring the effects of this method on the lungs during the perioperative period using electrical impedance tomography (EIT) is a highly useful tool. EIT, a non-invasive, radiation-free bedside monitoring system that detects real-time regional ventilation changes, can be used to guide individualized protective ventilation strategies to reduce perioperative respiratory system complications. Examining ROI values measured by EIT shows the effect of ventilation strategies on the distribution of tidal volume in the lungs. ROIs calculated by selecting layers, with ROI 1 and ROI 2 reflecting the ventral parts and ROI 3 and ROI 4 reflecting the dorsal parts, can be used to demonstrate the effect of the chosen ventilation strategy on lung gas distribution through intergroup comparison.

The age, gender, height, weight, body mass index, diagnosis, ASA score, preoperative hemoglobin level, additional systemic diseases, smoking history, prostate-specific antigen level, Gleason score, and prostate volume of the patients will be recorded. All patients will be monitored with electrocardiogram (ECG), peripheral oxygen saturation (SpO2), invasive arterial pressure (systolic arterial pressure, diastolic arterial pressure, and mean arterial pressure), and electrical impedance tomography. Patients will be prospectively randomized into two groups; group assignments will be determined using a closed-envelope technique.

All patients will be preoxygenated with 80% FiO2, followed by induction of anesthesia with 2 mcg/kg fentanyl, 2 mg/kg propofol, and 0.6 mg/kg rocuronium. After orotracheal intubation, patients will be placed on mechanical ventilation in volume control-autoflow mode with 8 ml/kg tidal volume, 2 L/min fresh gas flow, 0.4 inspired fractional oxygen (FiO2), an inspiratory: expiratory ratio of 1:2, and a respiratory rate to achieve normocapnia (partial carbon dioxide pressure PaCO2: 35-45 mmHg). Recruitment maneuvers will be applied to all patients.